A. Field of the Invention
The present invention relates generally to transportation vehicles or trains which travel along a guideway or track, and more particularly to an air levitated train of novel construction designed for high speed travel between metropolitan centers, steep banking around curves, and very low levitation air leakage.
B. Description of the Prior Art
A variety of guided vehicle systems have heretofore been proposed, often with the function of high-speed travel over long distances foremost in mind. In these various systems, it is known to utilize pressurized air for levitating the vehicle above a guideway to avoid friction between the vehicle and guideway, and for propelling the vehicle along the guideway.
Examples of air-levitated vehicles may be found in the following U.S. patent documents:
U.S. Pat. No. 3,090,327 to Crowley is directed to an air-levitated vehicle including a passenger car and a hollow, downwardly open pressure chamber beneath the car. A lift engine located on top of the car communicates with the pressure chamber via a vertical duct through the center of the car to provide pressurized air within the pressure chamber to lift the car slightly above a concrete track. The track defines a central peak formed by a pair of inclined lateral surfaces, with fore and aft walls of the pressure chamber forming a complementary configuration. In a modified embodiment of this vehicle designed for emergency stopping at high speeds, the pressure chamber is provided with an inner wall formed of brake lining material in complementary configuration to the track and having holes therethrough for escape of pressurized gas to lift the vehicle, and the inclined surfaces of the track are covered with stainless steel facings.
A high-speed rail system is described in U.S. Pat. No. 3,238,894 to Maksim and includes a vehicle suspended between oppositely disposed parallel guideways. Each guideway includes a pair of converging air bearing surfaces connected by a central transverse surface, and the vehicle is provided with a plurality of protruding fins complementary to the air bearing surfaces. The fins are configured to entrap a thin wedge-shaped film of air forcing against an associated air bearing surface of the guideway to support the vehicle without mechanical contact with the guideway when the vehicle is moving at a high rate of speed. The vehicle further includes wheels arranged to to engage longitudinal grooves in the central transverse surface for travel at lower speeds. Propulsion is by reaction engine or propeller.
Another air-supported vehicle system is disclosed in U.S. Pat. No. 3,308,767 to Hall, and is designed for installation over existing railways. This system includes parallel fluid bearing rails of tubular construction on the outside of the existing rails for receiving strut members connected to opposite sides of a train car, with pressurized air being supplied to the fluid bearing rails by an on-board compressor to provide a film of air between the strut member and bearing wall.
The vehicle system of U.S. Pat. No. 3,534,689 includes a passenger car suspended from an overhead tubular track for rotation about the longitudinal axis of the track, wherein lifting and centering of a passenger car mounting block about the track tube is achieved by diverting air from cells surrounding the underside of the tube to create subatmospheric pressure therein. A motor-driven propeller is employed as propulsion means.
U.S. Pat. No. 3,799,061, while not specifically directed to high-speed transport, nevertheless discloses a vehicle system comprising an overhead tubular track, and a vehicle suspended from the track by a pair of roof-mounted curved members bearing on the track tube by way of pressurized air cushions supplied by on-board air compressors and permitting rotation of the vehicle about the longitudinal axis of the track tube. Propulsion is conventional in nature, i.e. by linear electric motor.
U.S. Pat. No. 3,952,666, in particular at FIG. 3, teaches a vehicle having a pair of lateral curved shoe members received within parallel slotted guideway tubes supplied with pressurized air from a guideway supply pipe, wherein the vehicle is confined to tilt through curves only to the extent the guideway tubes are banked. The guideway tubes include a concave trough under the respective shoe having nozzles for creating a wedge of pressurized air under the shoe. Propulsion by a "linear pneumatic motor", or by conventional on-board jet engines, is contemplated.
Examples of pneumatic propulsion systems are also found in the prior art. Notable teachings include that of U.S. Pat. No. 3,242,876 to Berggren, and that of U.S. Pat. No. 5,542,357.